#include "myStdio.h"

FILE_ *fopen_(const char *path_name, const char *mode)
{
    int flags = 0;
    int defaultMode = 0666;
    if (strcmp(mode, "r") == 0)
    {
        flags |= O_RDONLY;
    }
    else if(strcmp(mode, "w") == 0)
    {
        flags |= (O_WRONLY | O_TRUNC | O_CREAT);
    }
    else if(strcmp(mode, "a") == 0)
    {
        flags |= (O_WRONLY | O_APPEND | O_CREAT);
    }
    else
    {}
    int fd = 0;
    if(flags & O_RDONLY)
        fd = (path_name, flags);
    else
        fd = open(path_name, flags, defaultMode);
    if(fd < 0)
    {
        const char *err = strerror(errno);
        write(2, err, strlen(err));
        return NULL;
    }
    FILE_ *fp = (FILE_ *)malloc(sizeof(FILE_));
    assert(fp);

    fp->flags = SYNC_LINE;//默认设置为行刷新
    fp->fileno = fd;
    fp->cap = SIZE;
    fp->size = 0;
    memset(fp->buffer, 0, SIZE);

    return fp;//为什么我们打开一个文件，就会返回一个FILE*指针
}
void fwrite_(const void *ptr, int num, FILE_ *fp)
{
    //1. 把数据写入到缓冲区中
    memcpy(fp->buffer + fp->size, ptr, num);// 这里我们不考虑缓冲区溢出的问题
    fp->size += num;
    // 2. 判断是否要刷新
    if(fp->flags & SYNC_NOW)
    {
        write(fp->fileno, fp->buffer, fp->size);
        fp->size = 0;//清空缓冲区
    }
    else if(fp->flags & SYNC_FULL)
    {
        if(fp->size == fp->cap)
        {
            write(fp->fileno, fp->buffer, fp->size);
            fp->size = 0;
        }
    }
    else if(fp->flags & SYNC_LINE)
    {
        if(fp->buffer[fp->size - 1] == '\n')// abc\nnefg,不考虑
        {
            write(fp->fileno, fp->buffer, fp->size);
            fp->size = 0;
        }
    }
    else 
    {}
}
void fflush_(FILE_ *fp)
{
    if(fp->size > 0)
        write(fp->fileno, fp->buffer, fp->size);
    fsync(fp->fileno); //将数据，强制要求OS进行外设刷新
    fp->size = 0;
}

void fclose_(FILE_ *fp)
{
    fflush_(fp);//刷新
    close(fp->fileno);//关闭
}